Slow screen refresh with Citrix Receiver 4.0 or 4.1 with old Citrix Farms

I was having an issue with very slow screen redraws with Citrix Receiver 4.1 with a MetaFrame 4.5 farm (although I've read online it's applicable to Presentation Server 4.0).  The fix is to enable the following registry key:


:Fix for slow graphics performance on Legacy Farm
IF '%PROCESSOR_ARCHITECTURE%'=='x86' (
reg add "HKEY_LOCAL_MACHINE\SOFTWARE\Citrix\ICA Client\Engine\Lockdown Profiles\All Regions\Lockdown\Virtual Channels\Seamless Windows" /v DeferredUpdateMode /d False /f
) ELSE (
reg add "HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Citrix\ICA Client\Engine\Lockdown Profiles\All Regions\Lockdown\Virtual Channels\Seamless Windows" /v DeferredUpdateMode /d False /f
)

Adding that key resolved the issue and now Citrix Receiver 4.1 now updates correctly on the 4.5 farm.